As part of manufacturing inner assemblies for electronic devices, in particular electronic devices for medical implants which are intended to be implanted into a human or animal body, it is generally necessary to fixate the electronic printed circuit board (“PCB”) to mechanical support features in the assembly. This is necessary to ensure that the electronic device does not move around under normal use conditions including insertion into the device housing, thereby imparting stresses to the solder joints and components. These stresses can lead to cracks with crack growth ultimately leading to interconnect failures. Further, because of the very limited size of an implant, the electronic device has to be significantly miniaturized, thus leaving virtually no free real estate on the printed circuit board.
Several approaches have been deployed over the years to achieve fixation of the circuit boards to mechanical support features, such as, providing clips on the mechanical support frame to retain the circuit board, providing thermal staking of polymer pins from the support frame onto the circuit board, providing adhesive tapes (e.g., Polyimide tape) to retain the circuit board in position, and providing thermally cured adhesive resins to glue the PCB onto the support frame. Clips on the mechanical support requires complex mechanical support frame mold tool design (to form the clips) and use of substrate real estate to form “shelves” to provide counter-force to support the clip forces. Providing thermal or ultrasonic staking of polymer pins from the support frame onto the circuit board requires use of larger board real estate to capture the staking and for the staking tool to form the pin. This approach also uses high temperatures or vibrations in proximity to possibly sensitive components, such as, for example, multi-layer ceramic capacitors (“MLCC”). The use of adhesive tapes to retain the circuit board in position requires difficult tape handling and positioning operations and may not lead to firm retention of the printed circuit board in its intended position. The use of thermally cured adhesive resins to glue the PCB onto the support frame requires use of adhesive resins which generally have long cure/cooling cycle times of more than 10 minutes and high temperatures, up to 125° C., which can damage or warp other components, such as the polymer frames.
The present invention is directed toward overcoming one or more of the above-mentioned problems.